Strengthening effect and mechanism of Fe doping on CuCr alloys during liquid-phase sintering

This study focuses on the microalloying effects of iron in CuCr alloys prepared via liquid-phase sintering, with a comparative analysis of the changes in composition, microstructure, and properties before and after Fe doping. The research finds that Fe microalloying in CuCr alloys can be achieved through liquid-phase sintering coupled with copper infiltration. Fe mainly combines with Cr in solid solution or compound form and preferentially segregates at the Cu/Cr two-phase grain boundaries. The doping of Fe acts as a bridge, promoting the diffusion of Cu into the Cr phase. As a result, spherical Cu particles appear within the Cr-rich phase of the Fe-doped alloy, and the Cr-rich phase becomes progressively refined. Meanwhile, finely dispersed Cr phases are observed in the Cu-rich phase of the CuCrFe alloy, which serve as second-phase strengthening particles in the Cu matrix. Compared to the requirements of GB/T 24269–2009, the prepared CuCr47Fe3 alloy exhibits improvements in relative density, electrical conductivity, and hardness by 0.87 %, 39.5 %, and 33.3 %, respectively. These enhancements are primarily attributed to the reduction in the Cu-Cr interfacial binding energy from −33.46 eV to −33.91 eV due to Fe doping, resulting in better interfacial bonding between Cu and Cr and a more stable product system.